Adding devices in today's environment to a data processing system made up of a multi-ported computing installation typically involves intricate detail and elaborate operations. The use of the term adding is not meant to include a physical hardware connecting operation. In fact, it is to be assumed that a preliminary operation has been performed and to-be-added devices are already cable connected and/or plugged in. With this in mind, the term adding is meant to include the operation of defining the devices to the operating system in use by the processing system such that the devices can be used by the operating system. In addition to defining new devices, also contemplated is the redefining of existing devices. The devices contemplated include keyboard/display input/output (I/O) terminals, direct access devices, tapc units, printers, card readers, card punch units, etc.
FIG. 1 depicts the intricate detail and elaborate operations mentioned above. Included are system programmer operations of writing detailed source code statements defining a device to be added or redefined and also the related control units and channels to be affected by the device, compiling the source code statements, and combining the resulting object code modules with other operating system components to generate a new operating system base. These operations are depicted by blocks 1, 2 and 3, respectively. The process encompassed in blocks 1-3 is often referred to as a system generation or SYSGEN operation. Because of the complexity of this process, there is a probability that mistakes will occur and it is usually prudent to subject the new operating system base to a degree of testing, as indicated by block 4, prior to its use in a production environment. This testing time represents time in which the computing installation or system is not available for its normal purpose.
At a very minimum, it is necessary to reload and reinitialize the operating system, as indicated by block 5, before the added or redefined device can be used. If the operating system, due to a mistake or whatever reason, fails to accept the definition, the system programmer operations must be repeated. Not only is system programmer time and effort costly, the effects of a down system can be disastrous.
One solution in attempting to eliminate the need for the SYSGEN operation is to predefine large numbers of potential devices at specific addresses. However, there are practical upper limits on the number of each device type which can be defined in this way. Also, device addresses must then be changed when new features are added to the devices. Further, and more importantly, the resources which are required in the operating system to define all unused devices are wasted from the time of the initial system installation until the time devices are actually physically attached.
The above is prior art only in a background sense, and as such, falls short of either anticipating or rendering the instant invention obvious. More specifically, the instant invention presents an advance over any known prior art in that a system can be reconfigured on-line and on a real time basis for a previously undefined device which is to be added. Further, the instant invention presents an advance in that the added device is instantly available for use by the system.